My 10-yr. old son asked me to leave his father!

My husband was diagnosed with ADD a little over three years ago after 11 years of marriage.  His diagnosis and treatment came about not because he thought he had any problems but because I finally kicked him out of the house and changed the locks...due to his agressive behavior and verbal abuse, which both my sons witnessed from the time they were born.  After my husband was diagnosed by our therapist and put on Adderall, he began to at least try really hard to be a good partner and he is usually a really good father.  He is not always aware of the things he says and at night (when his meds wear off) he sometimes says things to the boys or yells at them for no reason or "because he is watching TV"!  There are constanct communication problems between us to the point that the boys (who are 10 and 5) get involved and take sides.  He also has sleep issues that he will not address.  He is not treating all of the issues that surround his ADD.  He takes the same medication and dosage that was prescribed three years ago with no adjustments and monitored by a recent counselling since he moved back in and no other therapy.  I have been doing a lot of research and reading on ADD and when I try to talk to him, he acts as if he already knows everything and he's just fine now.  He says I am the one who needs to "get over" the last fourteen years of anger and abuse because he has changed and I should give him credit for taking his meds at all.  There are days that are wonderful and days (like today) that are horrible.  There are times when he apologizes for the past and we discuss the negative impact that these behaviors are having on our children and he seems to really "get it".  We discuss parenting techniques....but there is no follow-through!  Then there are days when he is still in denial or where he will tell the boys their mother is "crazy" or "psychotic" and tell them he is leaving me.  He uses them as a tool to get back at me when he is angry.  This morning, he was getting ready for his "vacation" which consists of a week or more, every year, that he takes off to go deer hunting.  I should mention that 2/3 of his "vacation" time from work is spent on himself and the boys and I take  a lot of mini-vacations separate from him.  In the past this is always a problem as he doesn't actually "go" anywhere...he hunts on our property!  Which means he is in and out of the house and up at 5am regardless of whether the boys have school or I have work.  He usually wakes up the whole house.  He comes home at night, only to "go out with the guys" again..leaving the boys crying or upset because he doesn't spend time with them.  It is a disaster.  This year, we talked about options such as staying with a friend or relative and he agreed...until today.  This morning, at 5:30am he started banging around the house "getting ready" for this weekend.  When I tried to remind him of our discussion, he turned on me...he had not taken his meds yet.  It got pretty bad...with him yelling and calling me names and he even told the boys thier mother was a b***h who was ruining his life.  He told them that he was leaving because no one should have to live with someone like me.  He told them I was a bad mother and they deserved better.  When he left for 10 yr. old told me that we shouldn't be married and asked me if I would divorce "Dad" so we could be happy.  My 5 year old said, "yeah daddy is really mean to you mommy and I hate him."  My 10 yr. old son said, "I know Dad has mental issues and I wish he would just get better...if you leave him maybe he will."  How do I handle this?  I dropped the boys off at school and then, finally, cried for an hour.....?  During the entire rampage this morning I tried to stay calm...but I admit that at the end I told him to get out and leave me alone (I actually shouted it).  This is not who I want to be and this is not what I want my boys to see.  They are going to model his behavior because he is their father.  I just don't know how to address this or what to do next.  How do you MAKE someone care enough to take the next step?  And what do I say to my boys?